The invention relates to the bill-posting industry and, more particularly, to the animated bill-posting sector, which works by unwinding a fabric comprising a number of juxtaposed panels. It relates more particularly to a structure of a bill-posting device which works by unwinding and which allows the use of very large-format bills which can, in particular, be used out of doors.
At the present time, there are two main known techniques which operate on the principle of dynamic bill posting, that is to say of scrolling through a number of bills mounted on one and the same information carrier.
Thus, in the field of public bill posting, advertising hoardings are known which form box structures equipped with a window behind which a strip consisting of a number of juxtaposed bills scrolls.
More specifically, a strip such as this is initially wound onto a first roller, and its free end winds onto a second roller which is motorized in synchronism with the first.
These two rollers are actuated to make the strip scroll past and to stop the strip to make the bill posting zone coincide with the window.
Devices such as this are described in particular in patents FR 2 735 602 and FR 2 771 537.
The bills used in this kind of device consist of printed panels joined together to form the actual bill.
The use of bills which are printed on paper constitutes an obstacle to making such devices in very large format. This is because when the number of joins to be made between the printed panels exceeds a certain limit, the operations involved in forming the actual bill become lengthy, painstaking and may even cause distortions in the quality of the image.
Furthermore, when a very wide paper bill is being wound up, creases often occur and these detract from the appearance of the image and may go so far as to cause tearing.
What is more, the creases constitute extra thicknesses when the strip is being wound up, and these can cause the winding system to become deformed or to jam.
Furthermore, converting such unwinding panels to very large formats entails the use of box structures which are, of necessity, bulky, and which have a window which is difficult to handle because it is heavy, and which is particularly exposed to the risks of vandalism.
There is a second known technique employing dynamic bill posting and which is essentially used for advertising installed around the field or pitch at sports venues.
Such devices are spread around the edge of the pitch so that they are in the field of view of the television broadcasting cameras, and the mechanism for unwinding the bill is actuated as broadcasting progresses, according to the way in which the advertising space has been rented.
Because of their exposure to the risks of impact, such devices have to be able to withstand great forces and are therefore of relatively modest size. More generally, such devices are equipped with a solid panel installed behind the information carrier and intended to provide it with the rigidity it needs to withstand impact.
The design of such devices opposes uprating them to large sizes, because the information carrier is not taut and because it is therefore subject to external constraints, such as windage, which prevents suitable winding.
Furthermore, the presence of such a panel is incompatible with the possibility of backlighting a bill to make it visible in the dark.
The objective that the invention is aiming at is that of providing an unwinding bill-posting device which can be read across to a number of formats, particularly large-sized formats, while at the same time being capable of withstanding the atmospheric phenomena likely to deform the bill and lead to the formation of creasing, which are particularly prejudicial to the quality of the winding.
The invention therefore relates to a device for posting bills by unwinding a fabric carrying information, in which the fabric is wound and unwound around two motorized and synchronized rollers in such a way that the fabric is kept under tension as it is unwound.
The device according to the invention is characterized in that:
the top end of the fabric is mounted removably on a fixing module secured to the upper roller;
the fixing module is connected to the upper roller by an unwinding mechanism allowing the fixing module to be moved down close to the lower roller for fitting and removing the top end of the fabric;
it comprises means for keeping the fabric under transverse tension.
In other words, in the bill-posting device according to the invention, the bill is fitted around the drive rollers using a special-purpose element which is mechanically detachable from the upper roller, to make the fitting operations easier by bringing this fixing module closer to the bottom zone of the unwinding panel, that is to say close to the lower roller.
Actuating of the upper roller therefore brings the fixing module back up and secures the top end of the fabric to the upper roller.
Furthermore, by virtue of the means for keeping the fabric under transverse tension, this fabric is capable of withstanding the forces generated by drafts or any other atmospheric disturbance, without its geometry being greatly modified.
Thus, the fabric can be wound up very uniformly, without any creases being able to arise near the winding zone, whether this be the upper roller or the lower roller.
This advantageous arrangement is further improved when the fabric is made of an extensile plastic, such as a film of polyvinyl chloride or of polypropylene or of polyethylene, for example.
This is because, in such a scenario, the fabric can undergo slight deformation in curvature due to the action of the wind for example, but this deformation is easily cancelled by the longitudinal tensioning exerted by the upper and lower rollers during the winding operation.
However, the invention also covers the alternative forms of embodiment in which the fabric consists of a relatively inextensile coated woven fabric.
Advantageously in practice, the fixing module may consist of a section piece which has a groove capable of accommodating and of holding beading mounted on the top end of the fabric.
In that way, the fitting of the fabric is made easier using a mechanism such as the one described in patent EP 0 294 301. A section piece such as this has the essential advantages of making it easy for the fabric to be fitted and of providing very good resistance to pulling-out forces.
Nonetheless, in other forms of embodiment, the fixing module may operate according to different principles, while still remaining within the scope of the invention.
Advantageously in practice, the unwinding mechanism connecting the fixing module to the upper roller may consist of a number of straps secured to the upper roller by their first end, and to the fixing module by their second end. The straps may be replaced by any equivalent means, and particularly by cables.
These straps wind and unwind around the upper roller depending on whether the fixing module is lowered for the operation of fitting of the bill, or raised up for winding the fabric onto the upper roller.
Advantageously in practice, the upper roller comprises zones of smaller diameter intended to accommodate the straps when the fabric is wound up, so that once wound up, the straps do not protrude beyond the main diameter of the roller.
In other words, as they are wound up, the straps become incorporated into a zone formed for that purpose in the upper roller, so that it does not cause any extra thickness on the diameter of the upper roller, as this would cause the fabric to deform as it was being wound up.
According to one feature of the invention, the upper roller has a housing capable of accommodating the fixing module as the fabric is wound up.
In other words, when the bill is well on its way to being in contact with the upper roller, and the fixing module is near the upper roller, it becomes set into this longitudinal housing in the roller.
Advantageously in practice, the fixing module and the housing intended to accommodate it have a geometry such that when the module is in place in said housing it does not protrude beyond the diameter of the upper roller.
Thus, the upper roller has a geometry which is as cylindrical as possible, so as to allow the fabric to be wound up smoothly and uniformly without causing creases to form.
According to one feature of the invention, the means for keeping the fabric under transverse tension consists of:
lateral beading mounted on the edges of the fabric;
a pair of section pieces arranged facing said edges, each section piece having a groove inside which the beading can slide, said groove being arranged in such a way as to prevent the beading from coming out under the effect of tension exerted at right angles to the section piece.
In other words, the fabric has beading which is present on its vertical edges and via which it collaborates with fixed members secured to the unwinding device.
Although the lateral guidance of the fabric gives rise to friction phenomena which somewhat increase the power needed to operate the bill-posting device, this lateral guidance does, on the other hand, practically eliminate any risk of creasing when winding the fabric onto the upper or lower rollers.
In a preferred form, guidance is obtained through the collaboration of beading and of a section piece forming a slideway, but other embodiments may be adopted such as, for example, the use of perforations at the edge of the fabric collaborating with toothed rollers arranged in the path of the lateral edges.
Advantageously in practice, the end of the upper and lower rollers is of smaller diameter, so as to take the extra thickness formed by the winding of the lateral beading.
In that way, as the fabric is gradually wound up, the lateral beading is also wound up at the end of the roller, and the extra thickness formed is compensated for by the difference in diameter.
Advantageously in practice, the ends of the upper and lower rollers are conical.
It has been found that the device operated optimally when the lateral beading used was longitudinally nondeformable, because the friction phenomena which occur when the beading slides in the lateral section piece are relatively low.
Specifically, as the fabric used is advantageously elastic, the nondeformable lateral beading provides a certain degree of longitudinal rigidity which prevents the fabric from jamming as it is wound up and prevents it from deforming excessively.
Advantageously in practice, the means for keeping the fabric under transverse tension are adjustable for width, to allow them to be adapted to suit slightly differing types of bill, or alternatively to suit particular atmospheric conditions for which it is necessary to adjust the acceptable limits on the deformation of the bill.
In another form of embodiment, the means for maintaining transverse tension are associated with means making it possible to increase the transverse tension in the fabric when the latter is immobilized.
Specifically, in certain instances, it may be advantageous to tension the bill not only in its longitudinal direction using the rollers but also by exerting tension at right angles to its direction of travel when the fabric is halted at the zone that is to be posted.
In one particular embodiment, the device comprises means for fixing the four corners of the fabric to the upper and lower rollers.